In modern mobile radio technology it is often necessary for mobile stations to support two different mobile radio standards. For instance it is known that mobile stations are designed to support the radio standards GSM (Global System for Mobile Communication) and UMTS (Universal Mobile Telecommunications System). GSM is a second generation radio standard, referred to as a 2G standard. A further development of the GSM standard is implemented by the extension GPRS (General Packet Radio Services) and EDGE (Enhanced Data Rates for GSM Evolution), which are referred to as 2.5G standards. UMTS, on the other hand, is a third generation radio standard, and is referred to as a 3G standard. Another third generation mobile radio standard is the TD-SCDMA radio standard (Time Division Synchronous Code Division Multiple Access), which is designed in particular for the use of mobile radio in Asian countries. In addition to the GSM standard, it is therefore necessary for mobile stations to be designed to also support at least the TD-SCDMA standard as well.
To enable a smooth transition from so-called 2.5G systems to 3G systems, such mobile stations are designed as multi-mode systems. However, this requires an enormous development effort and can currently only be realized with a substantial outlay for hardware. Separate hardware elements are provided in the mobile station for every radio standard to be supported. As a consequence, there is a limit to how much smaller the mobile stations can be built, and in addition it is relatively costly. One direct approach to developing a mobile station that supports both the GSM and TD-SCDMA standards is the use of a coprocessor in which the communication standards are processed in separate hardware blocks. This approach is however extremely costly to implement, and is also very unsuitable for implementing the software required. Instead of using a coprocessor, another approach is based on an integrated solution in which the baseband signal processing for 2.5G systems and 3G systems is executed within one chip, with separate blocks also being required here for the different radio standards, which results in a relatively large chip area.